Index of Refraction and Velocity

[drillers]

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So this may just be a pretty stupid question, but is it that n=c/v is an equation that only applies to electromagnetic waves and not to longitudinal waves such as sound and water.

I was working on an EK problem and as the index of refraction increased from air to a glass substance:

an electromagnetic wave's velocity decreased

a sound wave's velocity increased.


When I think about it, it does make obvious sense that sound travels faster in solids than gases, but the index of refraction equation threw me off because as n increases v decreases.
Any thoughts?

 

[going2breakdown]

Light is unique. When light enters a medium with a higher index of refraction 👎 it slows the light down to below it's maximum speed 3 x 10^8 m/s. So going from air into glass the light's speed "slows down" compared to it's speed in air.
SOUND is a wave caused by a vibrating source. It just so happens, generally, sound waves travel faster in solid, slower in liquids, slowest in air. That's just the nature of sound. It's a fact you have to memorize.
Light is unique, in fact, it needs no medium to travel. If it did, we wouldn't exist.

btw c=3.0 times ten to the eighth is it's speed in a vac. not in air. For all intents and purposes remember if it's in air it's n=1.

 

[gettheleadout]

If you want a corresponding equation to predict mechanical wave (e.g. sound) velocity in media, see here: http://hyperphysics.phy-astr.gsu.edu/hbase/sound/souspe2.html#c1

 

[drillers]

If you want a corresponding equation to predict mechanical wave (e.g. sound) velocity in media, see here: http://hyperphysics.phy-astr.gsu.edu/hbase/sound/souspe2.html#c1

Thanks to both of you for the help!